The difference is ESPN has reported the NCAA is investigating whether Manziel, the Texas A&M quarterback, got paid to sign autographs, which would violate amateurism rules. That has led to other schools being asked questions about whether their players earned money for signatures.

If the allegations against Manziel, made by unidentified sources to ESPN, are proved true by the NCAA, his eligibility for the coming season could be in doubt as well as his status as a Heisman winner.

ESPN reported that a top autograph authenticator had authenticated nearly 1,000 Manziel autographs.

Brandon Steiner of Steiner Sports, which is the official collectible and memorabilia company of the NBA, the New York Yankees and Notre Dame, among others, said his company does not do business with college athletes.

He said Manziel would likely be able to sign a contract with a collectibles company of at least $100,000 after he went pro.

"I know there is a vibrant Heisman Trophy collectible audience out there," he said.

A market flooded with Manziel autographs could cost him money later, Steiner said.

"It creates market confusion and takes a lot away from the category," Steiner said Wednesday.

Other college athletes might want to take note.

Two sports websites — bustedcoverage.com and goodbullhunting.com — found what appeared to be dozens of authenticated items signed by Clowney online, and that led to questions for South Carolina officials.

Associate athletic director Chris Rogers said Wednesday the school's compliance office has looked into the Clowney autographs on eBay and found no violations had occurred.

"The websites that we've looked at and the pictures and autographs and items that we've found over the last academic year, we've not had any issues to suggest that anything impermissible had occurred," Rogers said.

Ohio State athletic director Gene Smith said school officials have determined Miller had not profited from the numerous items found online with his signature. Smith said the quarterback signed many autographs at a Big Ten preseason kickoff luncheon. Presumably fans or memorabilia brokers then went and sold items they got autographed for free.

"We've already looked at it," Smith said. "There's no issue there."

Louisville came to a similar conclusion.

"We are aware of many of the items for sale online that have been autographed by several of our student-athletes with remaining eligibility. As we are required to do by NCAA rules, we regularly review these items and send correspondence to the seller(s) requesting they remove the item for sale," the school said in a statement. "We have and continue to educate our student-athletes that it is not permissible to accept any type of compensation for their autograph or the sale of memorabilia. We have spoken with Teddy Bridgewater and we are comfortable that no violation has occurred."

Clowney, Bridgewater and Miller enter the season has prime contenders for the Heisman.

Manziel became the first freshman to win it last season. It's unclear if an NCAA violation would cause the Heisman trust to reconsider Manziel's victory.

Heisman Trust's rules state: "The recipient must be in compliance with the bylaws defining an NCAA Student-Athlete."

"The Heisman Trust never comments on speculation," Heisman spokesman Tim Henning said Wednesday.

Reggie Bush's 2005 Heisman Trophy was later vacated after the NCAA found he had received improper benefits during his winning season.